As a recording device for producing permanent records on plain paper, there have been known a variety of recording devices including electrophotographic copying machines and thermal transfer printers. Such recording devices are described in patents and other literatures. For example, Japanese patent publication No. 40109/1986 discloses an electrophotographic copying machine employing electrophotography. In the electrophotographic recording, a photosensitive drum is charged with a corona discharger to produce uniform distribution of electrical charges and then exposed to a light pattern to form a latent electrostatic image on a photosensitive surface of the drum, and the latent image is developed with a powder developer into a visible powder image, transferred to a sheet of plain paper, and then fixed thereon by fusing to form a permanent copy.
Japanese patent publication No. 51998/1986 discloses a thermal transfer printer employing a thermosensitive inking tape and an electrothermal head. In this system, an inking tape in contact with the head is locally fused by signal-controlled thermal action of heat-generating elements of the head, and the fused ink is transferred to recording paper to produce a record.
However, the electrophotographic copying machines have complicated mechanisms since various units including a corona discharger, a light exposure unit, a powder developer, and a image transfer unit must be arranged around the photosensitive drum, resulting in a considerable increase in the manufacturing cost. The thermal printers are simplified in construction, but they require use of expensive inking tapes, resulting in increase in the recording cost per unit sheet.
On the other hand, there has been proposed a printer of the kind wherein a multi-element magnetic head is adapted to be in contact with a magnetic recording sheet, and applied with electric image signals to produce a latent pattern of magnetic dots on the recording sheet, and wherein the magnetic dot pattern is developed with a powder developer containing magnetic toners into a visible powder image, transferred to a sheet of plain paper, and then fixed thereon to produce a completed record. Japanese utility model laid-open No. 154515/1976 discloses a multi-element magnetic head for use in such a printer, comprising a plurality of magnetic elements each composed of a magnetic core and magnetic coils wound around each core. In such a recording head, it is required to provide a large number of magnetic elements of the head since the quality of record depends on the number of magnetic dots, or, the number of the magnetic elements of the head. However, the greater the number of dots, the greater is the number of the coils of the recording head, so that the recording head becomes complex to manufacture.